Some additional information, but still some unknowns about how the tanker blast actually occurred:
"The explosion prompted authorities to evacuate about 100 homes and 30 businesses— roughly one-third of the town’s population, by one official’s account — just west of Sioux Center’s business district. Emergency crews moved some residents to a nearby recreation center for shelter, said Jerry Holtrop, chief deputy for the Sioux County Sheriff. Fire and hazardous materials crews contained the flames by 7 p.m., but had not lifted the evacuation order.
“We were just telling them to leave their residences and find relatives in other towns,” Holtrop said.
David Krahling, a spokesman for the Sioux Center Fire Department, said the blaze had not damaged any buildings, and could not say with certainty what the tanker was holding. One person was taken to the Sioux Center Community Hospital with unknown injuries, he said.
Authorities had not yet pinpointed the fire's cause.
Five local volunteer fire departments and a crew from the Sioux City Fire Department Hazardous Materials unit responded to the blaze. Some residents said they could see the smoke from well beyond the half-mile evacuation radius.
The fire hit less than a block from the Centre Mall, with several shops and a movie theater, and a Fareway Store in one of the busiest parts of town.
Investigators have not yet concluded that ethanol started the fire, Krahling said.
Sioux Center, population 6,600, is located about 45 miles north of Sioux City in northwest Iowa."
This all happened close to some of the most populated areas of town and could have been much worse. Obviously, fire fighters and other officials did a great job getting people out and keeping the fire contained.